Conventional skin cleansing liquid products and shower gels, are usually thick liquids, packed in bottles, which are relatively slow foaming and produce very little, relatively weak foam which quickly flattens. Post-foaming gels such as shaving gels, use a soap-based system which may optionally contain a minor amount of surfactant. Prior art post-foaming gel shower products consist of conventionally thickened sodium lauryl ether sulfate (SLES) and fatty acid diethanolamide (CDEA) blended together with a low level of foaming agent, such as the liquified hydrocarbon and chlorofluorohydrocarbon propellants. A number of major problems are associated with this type of product. The gel provides a stringy, tacky feel; possesses very poor high temperature stability; is restricted to very low levels of foaming agent due to the thinning effect of foaming agents on said thickened SLES/CDEA base, which results in non-optimization of foaming properties; and the need for high viscosity bases to allow for thinning effect on the base from the foaming agent while still retaining a good gel, provides process difficulties when handling such viscous bases.
It has now been found that all of the aforediscussed problems and limitations of previous post-foaming shower products have been overcome by present novel post-foaming gel which provides a post-foaming gel for shower use, with rapid development, of copious amounts of foam.
The use of an aqueous soap-based post-foaming gel in personal care products such as shaving creams, shampoos and skin cleansing products is well known in the art as disclosed in U.S. Pat. No. 2,995,521 wherein is disclosed a thick aqueous soap composition with a liquified aliphatic hydrocarbon foaming agent.
U.S. Pat. No. 3,541,581 discloses an aqueous, preferably soap-based post-foaming gel, which may contain a nonionic or anionic surfactant-either in addition to the soap or instead thereof and, optionally, a water soluble gelling agent, and a liquid post-foaming propellant packaged in an aerosol dispenser wherein the active ingredients are separated from the propellant by a collapsible bag to avoid undesirable premature foaming.
British Pat. No. 1,444,334, discloses post-foaming aqueous, soap-based shaving gel compositions containing 0.5-8% of a water-soluble hydroxy alkyl cellulose or polyoxyalkylene gelling agent and optionally a nonionic or anionic surfactant; and 0.5-5% by weight of a post-foaming aliphatic and/or halogenated hydrocarbon agent; packaged in a conventional aerosol foam dispenser with a pressurized gas propellant in the head space to discharge the shaving gel.
U.S. Pat. No. 4,405,489 discloses a process and apparatus for the production of a stable aqueous post-foaming gel for packaging, based on an aqueous soap-containing or surfactant gel, preferably a soap based gel, and a post-foaming agent by intimately mixing and passing the mixture to a filling-machine for introduction into a container, using a continuous flow system under pressure and maintaining the mixture for a time and at a temperature and pressure sufficient to produce a post-foaming gel prior to the filling machine. A preferred additional ingredient is an oil sparingly soluble in water, such as a nonvolatile oily hydrocarbon and/or a liquid fatty alcohol and/or a fatty ester. The post-foaming gel comprises 40-80% water, 10-25% soap and 1.5-4% post-foaming agent, and about 0.25-1.5% oil.
Canadian Pat. No. 1,021,264 discloses anhydrous self-foaming shampoo compositions comprising 10-80% organic solvent (trichlorofluoromethane), which also functions as the foaming agent, 10-50% anionic or cationic surfactant and 0.1-15% of a film forming resin insoluble in water (methacrylate polymers, etc.), dispensed from a container as a liquid which forms a copious foam, when applied to wet hair at a temperature of about 75 degrees F. and above.
High-foaming anhydrous liquid detergent compositions, for use as shampoos, is also disclosed in U.S. Pat. No. 3,728,265, containing 10-25% of a liquified aliphatic hydrocarbon or halogenated hydrocarbon (propane, butane, etc.) dissolved in 10-25% organic solvent such as propylene glycol (water soluble), 30-45% anionic surfactant and 5-25% C.sub.6 -C.sub.12 fatty acid alkanolamide, packaged in a non-pressurized container, which produces profuse foam when mixed with water.
U.S. Pat. No. 3,705,855 discloses a pressurized water-in-oil emulsion which reverses to a stable oil-in-water emulsion and can foam a finite time after discharge from an aerosol container to be used as a shaving cream, said emulsion comprising two immiscible liquids in emulsified form having water in the dispersed phase and propellant in the continuous phase. The ingredients in the emulsion include a water-in-oil emulsifier such as sorbitan fatty acid esters, and nonionic and/or anionic water soluble surfactants.
U.S. Pat. No. 3,962,150 discloses an aerated, low density (0.01-0.10 gm/ml) aqueous, non-pressurized, foam-producing, skin cleansing composition consisting of anionic and nonionic surfactants, 1-15% of an alcoholic solvent and 70-98% water, and having a viscosity of 0.5 to 300 cps. The foam is extruded from the dispenser by squeezing the container causing the aqueous solution to leave the reservoir and enter an air-mixing or foaming chamber via an internal dip tube, wherein the foam is produced and passed through a homogenizing element to provide a foam of a uniform consistency when discharged from the container.
None of the aforesaid prior art discloses a post-foaming gel shower product based on an aqueous soap-free, surfactant-containing gel system containing an anionic alkali metal C.sub.10 -C.sub.16 alkyl ether sulfate surfactant, a water dispersible nonionic ethoxylated fatty alcohol or fatty ester, and about 5-20% by weight of a 2:1 blend of n-pentane and iso-butane foaming agent as an integral part of the gel structure. The anionic surfactant and the ethoxylated fatty alcohol or ester are present in a weight ratio of about 4:1 to about 1:4.